Many different types of mobile systems exist. Examples of such systems include cellular telephone handsets, personal digital assistants (PDAs), notebook personal computers (PCs), and the like. During the design and development of such systems, significant resources are spent to confirm that the design and its implementation operate satisfactorily, both in laboratory testing and in the field during normal operation.
With respect to cellular telephones, for example, certain design issues may lead to systemic errors or performance issues that cannot be resolved during design phases or analysis of development or other prototype systems. Instead, such issues often arise only in the context of production systems. As a result, the final round of test and validation for a cellular handset is a systemic problem. All of the components of the phone may meet their respective specifications, but the unit as a whole may fail to meet one or more performance criteria, for a number of reasons. Many of these integration problems are inherently systemic and cannot be reproduced on a reference design, a development platform, or another handset model. Instead, such problems are debugged “in vivo” on the given handset model, and in some cases a specific handset.
Effective system debugging requires some degree of visibility into the internal operation of the handset, which is limited on a production model. Typically, in vivo debugging of handsets is performed using an integrated test mode or a conventional trace facility. The integrated test mode typically provides limited diagnostic capabilities and only allows limited viewing of trace data on a display of the handset. Conventional trace facilities are typically accessed using a serial port of the handset, and the tracing is typically limited to analysis of data from an internal microcontroller unit (MCU). Such trace information does not provide any visibility into the physical layer (Layer 1 in the OSI communication model) or digital signal processor (DSP) data.
Instead, to obtain such data a handset manufacturer may sometimes modify a handset to provide greater visibility. However, such modifications are time consuming and are often ineffective. For example, these modifications can vary operation of a handset to conceal problems, and may destroy the handset. Certainly, these handsets cannot be sold after the modifications are made. Nor are they generally suitable for field-testing of specific phone issues.
Accordingly, improved diagnostics for mobile systems would aid and speed handset development and debugging.